Refrigeration



' QcLZG, 1937. A, THOMAS 2,096,828

REFRIGERATION Filed Nov. 9, 1934 Z'Sheets-Sheet 1 INVENTOR. y-

WWW-1M fi wwz A ATTORNEY.

Oct. 26, 1937. I H A 2,096,828

REFRIG-ERA'IIQN Filed Nov. 9, 1954 2 Sheets-Sheet 2 5 INVENTOR. .33 Maw/8. d m

4 ATTORNEY.

Patented Oct. 26, i937 UNITED STATES PATENT OFFICE 2,096,828 nnrmonm'rrou Application November 9, 1934, Serial N0. 752,234

14 Claims.

My invention relates to refrigeration and-more particularly to cooling-air in a refrigerator compartment. This application relates back for common subject matter to my earlier application Serial No. 643,975, filed November 23, 1932.

It is an object of my invention to provide a cooling element having an adequate extent of surface for maintaining air in a refrigerator compartment at a desired temperature. It is another object to provide a cooling element which may be positioned in the uppermost part of a refrigerator compartment for most advantageous cooling of air in the compartment.

A further object is to automatically provide refrigeration responsive to the demand therefor. Another object is to automatically maintain the temperature of air in a refrigerator compartment at a substantially constant temperature irrespective of variation in heat leakage into the compartment or other variation in heat load.

In accordance withmy invention, I provide in a, thermally insulated refrigerator compartment a cooling element havinga relatively limited surface for contact with air and normally 2"5 maintained at a substantially constant temperature which is preferably low enough for rapid freezing of water into ice, or the like. I further provide a condensation-evaporation circuit including an evaporator having relatively extensive surface for heat transfer from air in the refrigerator compartment, and a condenser arranged in thermal exchange relation with the low tempera-- ture cooling element. I. preferably positionthe extensive surface evaporator above the condenser and in the uppermost part of the refrigerator compartment, and provide for flow of liquid cooling fluid from the condenserto the evaporator by thermosyphonic action responsive to tempera ture of air to be cooled in the refrigerator compartment.

My invention, together with the objects and advantages thereof, will be better understood upon reference to the following description and accompanying drawings forming a part of this specification, and. of which:

Fig. 1 is a front elevation, with portions broken away, of a refrigerator embodying my invention;

Fig. 2 is a fragmentary section taken on line 2- -2 in Fig. 1; and

Fig. 3 is a. section taken on line 33 in Fig. 2. I

Referring to the drawings, in Fig. 1 I have shown a refrigerator l0 having a thermally insulated storage compartment ll accessible by means of a door l2, and a lower apparatus compartment accessible by means of a removable .producing refrigeration.

closure member I3. In the storage compartment I l is a cooling element, indicated generally by the reference numeral I4, which may be part of a refrigeration apparatus, for instance, of a pres- I sure equalized absorption type. 5 Briefly, a refrigeration apparatus of this type may comprise a generator and absorber interconnected for circulation therebetween of an absorp-'- tion liquid, and an evaporator interconnected with the absorber for circulation therebetween 10 of an inert auxiliary gas. A refrigerant fluid, soluble in the absorption liquid, is vaporized out of solution by heating in the generator, and the vapor is liquefied in a condenser. The 1i uid refr'igerant is conducted to the evaporator where 15. it evaporates and diffuses into the inert gas, In the absorber, the refrigerant vapor is absorbed out of the inert gas into the absorption liquid. The evaporator may be maintained at a substantially constant 20 the flue l5. Gas is supplied to the burner l5 from a conduit l'l through a gas filter I8 and a ermostatic valve IS. The latter is operated in 35 known manner by an expansible fluid thermostat including a capillary tube 2| connected to a sensitive bulb 20 which is located in thermal contact on the cooling element l4, so that the valve 19 is operated responsive to temperature of the 40 cooling element It. The thermostatic valve, l9.

maybe adjusted by a knob 23 on the upper part 'of the front baflle plate of the cooling element l by means of ,a flexible cable arrangement 24, of k which the lower end maybe seen in Fig. 1 and the upp r .end in Fig.2.

The cooling element, comprises a-pipe coil 34. which may be embedded in a metal casting 2 5. The coil 34 may be formed in a plurality of super- 50 posed substantially horizontal U-shaped loops, generally as described in an application Serial No. 645,422 of Sven W. E. Anderssonand William R, Hainsworth. The casting 25 provides recesses for ice freezing trays 28. The thermostat bulb 20 is 66 preferably located in good thermal contact on the bottom of the casting 25. The casting 25 is formed with a plain outer surface affording relatively limited surface for heat transfer from air in the refrigerator compartment H.

In accordance with my invention, I provide a further element for cooling the air in the refrigerator compartment H and comprising-a tube 26 having an extensive heat transfer surface formed by a plurality of fins 21. The finned tube 26 may advantageously be positioned directly above the casting 25 as shown in Figs. 2 and 3. However, the finned tube 26 may be otherwise located and may be of any desired length or configuration depending upon the size 'of the refrigerator compartment to be cooled, and, therefore, the heat transfer surface necessary. The finned tube 26 may be referred to as an evaporator.

Also embedded in a side wall of the casting 25 is a pipe coil 29. The upper end of the pipe coil 29, at the forward end of the casting 25, is connected to the forward end of the finned tube 26 at a point near the upper part of the latter, so that vapor produced in a process hereinafter described may flow from the finned tube 26 into the coil29. The lower end of the coil 29 is connected through a downwardly looped conduit 30 to the other end of the finned tube 26. One leg'32 of the downwardly looped conduit 30 is provided with a plurality of heat transfer fins 33. The finned tube 26, pipe coil 29, and the loop 36 are connected, as just described, to form a hermetically sealed circuit in which I place a suitable volatile fluid. The

coil 29, being embedded in the casting 25, is maintained at substantially the same temperature as that of the casting, and, therefore, functions as a condenser in which the fluid condenses to liquid, the heat of condensation being transferred through the casting 25 to the coil 34 of the refrigeration apparatus. The liquid flows from the lower end of the condenser coil 29 into the leg 3| of the looped conduit 30.

The liquid would normally stand at the same level in legs 3| and 32 of the looped conduit 33.

However, when the temperature of the air in the refrigerator storage compartment rises above the vaporization temperature of the liquid in the secondary circuit, heat is transferred from the air .through the fins 33 to the liquid in the leg 32 of the looped conduit 30. Thereupon, vapor is formed in the leg 32, causing the weight of the column of liquid in the leg 32 to become less than the weight of the column of liquid in the leg 3i. The looped tube 30 is constructed and arranged -so that the difference in weight of the liquid columns in the legs 3| and 32 causes an upward flow of liquid in the leg 32 and into the upper end of the evaporator 26. This action is usually referred to as thermosyphon action. The leg 32 may be formed with an internal diameter sufliciently small so that liquid and vapor cannot pass each other therein, whereby liquid is raised through the leg 32 by an additional vapor lift or pumping action.

i It will be understood that, as the temperature of the air in the storage compartment ll. rises, the vaporization, of liquid in the leg .32 will increase, causing a greater flow of liquid to the evaporator 26.. In the evaporator 26, liquid evap crates,- the heat of vaporization being transferred thereto from the air in the storage compartment through the extensive surface formed by the flns 21. The vapor returns from the evaporator 26 to the condenser coil 29, completing the cycle in the secondary circuit. The secondary cooling circuit may be arranged for operation at a desired temperature differential with respect to the temperature of the primary cooling element ll. For instance, a suitable fluid and an inert gas may be introduced into the secondary system, so that evaporation of the fluid in the evaporator 26 takes place at a temperature above that of the primary cooling element at which condensation occurs in the condenser coil 23. The evaporator 26 may be provided with sumcient heat transfer surface, and operated at a temperature above that at which water freezes, thereby obviating the formation of frost thereon and the resulting decrease in humidity of the air.

Assuming that the refrigeration apparatus is in operation, the thermostat l9 may be adjusted by turning the knob 23 so that the refrigeration apparatus operates to maintain the cooling element it, including the casting 25, at a desired constant temperature. The primary cooling element [4 may be maintained at a temperature considerably below the freezing point of water, so that water or other substance in the ice trays 28 may be quickly frozen by direct conduction of heat from the trays to the shelves formed by the casting 25. Air in the refrigerator compartment l l flows in contact with the outer surface of the casting 25 and becomes cooled thereby. However, the surface of the casting 25 is relatively small, and, upon increase in heat loads, as upon increased heat leakage into the refrigerator, may be insuflicient to maintain the air in the storage face of the evaporator 26, thus brought into effect,

tends to maintain the temperature of air in the storage compartment at the deslredtemperature. If the device is so constructed and arranged that the secondary circuit is at all times in operation, an increase in temperature of air in the storage compartment then results in increasing the supply of liquid cooling fluid to the evaporator 26 responsive to the increased demand for refrigeration. The result is that, for a given operating temperature of the primary cooling element H, the air in the refrigerator storage compartment is maintained at a substantially constant temperature. Furthermore, cooling of the air by the evaporator 26 is accomplished efficiently with a low temperature differential over an extensive surface in the uppermost part of the storage compartment where the air is the warmest and the maximum temperature differential exists for a given temperature of the evaporator 26.

Various changes and modifications will be apparent to those skilled in the art, wherefore my invention is not limited to that which is shown in the drawings and described in the specification but only as indicated in the following claims.

What is claimed is:

1. In a refrigerator, a cabinet having a thermally insulated storage compartment, refrigeration apparatus including a cooling coil in said compartment and means for maintaining said "cooling coil at a substantially constant temperaa tube having an extensive surface formed by fins, a conduit for vapor from said evaporator to the upper end of said condenser coil, a downwardly looped conduit connected from the lower end of said condenser coil to said evaporator, a plurality of heat transfer fins onthe leg of said looped conduit connected to said, evaporator, and a volatile fluid in the circuit formed by said evaporator, condenser and looped conduit.

2. In a refrigerator, a cabinet having a thermally insulated storage compartment, refrigeration apparatus including a cooling element in said compartment, a metal casting in which said cooling element is embedded and which forms a receptacle for ice trays, a condenser coil also embedded in said casting, an evaporator above said condenser, a conduit for vapor from said evaporator to the upper end of said condenser coil,

a conduit from the lower end of said condenser coil to said evaporator and forming a thermosyphon, and a volatile fluid in the circuit ineluding said evaporator and condenser.

3. In a refrigerator, a cabinet'having a thermally insulated storage compartment, refrigeration apparatus including a cooling element. in said compartment, a metal casting in which said cool.- ing element is embedded, a condenser also embedded in said casting, an evaporator above said condenser, conduit means interconnecting said evaporator and condenser in continuous circuit and forming a thermosyphon for raising liquid from said condenser to said evaporator, and a volatile fluid in said circuit.

4. A method of refrigeration which includes evaporating a first fluid in a place of thermal transfer relation with air to be cooled, condensing a second fluid by heat transfer to said first fluid, and delivering condensate of said second fluid to a certain further place of thermal transfer relation with said air to .be cooled only upon rise in temperature of the air to be cooled.

5. A method of refrigeration which includes flowing air in thermal transfer relation with a plurality of places of evaporation, continuously supplying refrigerant fiuidto one of said places of evaporation, and supplying refrigerant fluid to another of said'plac'es of evaporation in ac- I cordance with change in temperature of the air being cooled.

6. In a refrigerator having a thermally insulated storage compartment, a cooling element in thermal transfer relation with air in said compartment, means for maintaining said cooling element at a substantially constant temperature,

and a circuit including an evaporator also in thermal transfer relation with air in said compartment, a condenser below said evaporator and in thermal exchange relation with said cooling element, a conduit for vapor from said evaporator to said condenser, and a downwardly looped conduit having one end connected to said condenser and the other end connected to said evaporator,v

said conduit forming a thermosyphon for caus ing flow of liquid from said condenser to said evaporator.

7. In a refrigerator having a thermally insulated storage compartment, refrigeration apparatus including a cooling element in limited thermal transfer relation with air in said compartment and means for maintaining said cooling element" at a substantially constant temperature, a second cooling element in relatively, extensive thermal transfer relation with air in said compartment, and means for supplying refrigerant fluid to. said second cooling element responsive to change in temperature of air in 'said' compartment.

8. In a refrigerator having a thermally insulated storage compartment, a plurality of evaporators in thermal transfer relation with air in said compartment, means for continuously supplying refrigerant fluid to one of said evaporators, and means for'supplying refrigerant fluid to another of said evaporators in accordance with change in temperature of air in the compartment.

'9. A refrigerator having a thermally insulated storage. compartment, a cooling element in thermal contact with air in the compartment, means for supplying refrigerant to said cooling element, a second cooling element in thermal contact with air in the compartment, a condenser arranged in heat exchange relation with said first cooling element, and means connecting said second cooling element and said condenser to provide a closed fluid circuit containing a-fiuid adapted to condense in said condenser and evaporate in said second cooling element, said connecting means being so arranged and formed that fluid is supplied to said second cooling element from said" provide a closed fluid'circuit containing a fluid adapted to condense in said condenser and evapor-ate in saidsecond cooling element, said connecting means being so arranged and formed that fluid is supplied to said second cooling element from said condenser at airate which is dependent upon the demand for'ref rigeration in the storage compartment. I

11. A refrigerator having a thermally insulated storage compartment, a cooling element in thermal contact with air to be cooled, means for supplying refrigerant fluid to said cooling element, a-

second cooling element in thermal contact. with air to be cooled, and means including said second cooling element forming an independent closed fluid circuit for supplying a second refrigerant fluid to said second cooling element at a rate-dependent upon the temperature of theair in the storage compartment.

' 12. A method of refrigerationwhich includes the steps of continuously evaporating a first fluid in a place of thermal transfer relation with air to-be cooled, condensing a second fluid byheat transferto said flrst fluid, conducting the condensate of said second fluid to a second place of thermal transfer relation with air to be cooled in accordance with the demand for refrigeration determined by the temperature of the air to. be cooled, and evaporating the condensate of said second fluid at the'second place of thermal transfer relation with air to be cooled.

13- A refrigerator having a thermally insulated storage compartment, a cooling element in thermal contact with air in the compartment, means for supplying refrigerant to said cooling .element, a' closed fluid circuit including a second cooling element in thermal contact w h air in with said first cooling element, the fluid evaporating in said second cooling element and con-,

(lensing in said condenser, said circuit a part at a lower level than said second cooling including element and connected thereto and to said condenser for accumulating condensate formed in the latter, said part being in thermal contact with air in the compartment and so formed and connected to said second cooling element. that condensate formed in said condenser is supplied to said second cooling element only when said first cooling element is inefiective to maintain the air in the storage compartment at or below a predetermined temperature. I

14. A refrigerator having a thermally insulated storage compartment, a cooling element in thermal contact with air in the compartment, means for supplying refrigerant to said cooling element,

a being in a second cooling element disposed in the uppermost part of the compartment and at a higher level than said first cooling element, said second cooling element being in thermal contact with air in the compartment, a condenser arranged in heat exchange relation with said first cooling element, and means connecting said second coolin element and said condenser to provide a closed fluid circuit containing a fluid adapted to condense in said condenser and evaporate in said second cooling element, said connecting means thermal contact with air in the 'compartment and having a heat transfer'suri'ace and being so arranged and formed that condensate is supplied to said second cooling element from said condenser only when said first cooling element is ineffective to maintain the air in the storage compartment at or below a predetermined temperature.

ALBERT a 'rnoma- 2o 

